by IISD's SDG Knowledge Hub,

In their early years, children mouth a variety of products, such as toys, teethers, and pacifiers, all of which contain different chemical substances. When manufacturing children’s products, chemical additives such as plasticizers, flame retardants, and antimicrobials are used to obtain or optimize specific properties.

During mouthing, many of these additives can migrate from products into saliva since they are not covalently bound to the polymer chains. Thus, assessing exposure pathways in children, such as mouthing, is crucial. However, mouthing as an exposure pathway is often poorly quantified or neglected.
Available approaches for quantifying mouthing exposure for children require: measured chemical migration rate from the specific product into saliva; mouthing surface area; mouthing time; and body weight of the child. These approaches depend on availability of experimental migration rates that are not only chemical-specific but also dependent on the material itself, which might have a significant influence on the chemical migration rate.
The range of chemical-material combinations of children’s products currently being marketed, and other potentially relevant chemical groups and material types, which may all pose health risks to children, remain unaddressed. Since conducting migration experiments for each different chemical-material combination is costly and time consuming, mathematical estimation methods are needed to estimate migration rates for the thousands of chemical-product combinations.
Therefore, a study was undertaken and published as Estimating mouthing exposure to chemicals in children’s products. The study aims to develop a mouthing exposure model to predict migration into saliva, mouthing exposure, and related health risks from a range of chemical-material combinations in children’s products. It focuses on four objectives, namely to:

  • collect experimental data on chemical migration rates into saliva for different chemical groups and materials;
  • identify properties influencing chemical migration rates into saliva;
  • develop and evaluate a predictive model for migration into saliva and related mouthing exposure for a range of material-chemical combinations; and
  • derive exposure and related risk estimates for mouthing of children’s products for average and upper bound mouthing behavior scenarios and compare them to other exposure pathways for chemicals with available experimental data.

To predict migration rates into saliva, the study adapted a previously developed migration model for chemicals in food packaging materials, as well as a regression model based on identified chemical and material properties.

Regarding results, migration predictions correlate with experimental data and vary widely from, with plasticizers in PVC showing the highest values. The results suggest mouthing behavior has a significant influence on mouthing daily exposure and on potential risk. For an average mouthing scenario, potential risk was observed for a limited number of chemical-material combinations. However, with an upper bound mouthing behavior scenario, the number of combinations with potential hazards increased. For this reason, considering an average mouthing duration when assessing mouthing exposure might underestimate actual risk.

The study states that producers and regulators should guarantee the safety of both average and upper bound users when designing their products. The model represents a green and sustainable chemistry tool industries can apply to assess whether the chemicals present in their products could pose a risk to children, as well as to evaluate safer alternatives during the design process.

The study was published in the Journal of Exposure Science and Environmental Epidemiology It was supported by the Global Best Practices on Emerging Chemical Policy Issues of Concern under UN Environment’s Strategic Approach to International Chemicals Management (SAICM) and by the Safe and Efficient Chemistry by Design (SafeChem) project funded by the Swedish Foundation for Strategic Environmental Research. [Publication Landing Page]